setup.py: update url (#269)

setup.py

@@ -27,7 +27,7 @@ setup(name='mwclient',
       keywords='mediawiki wikipedia',
       author='Bryan Tong Minh',
       author_email='bryan.tongminh@gmail.com',
-      url='https://github.com/btongminh/mwclient',
+      url='https://github.com/mwclient/mwclient',
       license='MIT',
       packages=['mwclient'],
       install_requires=['requests-oauthlib', 'six'],